Synoptic Evaluation of Long-Term Antarctic Ice Sheet Model Simulations using a Continent-Wide Database of Cosmogentic-Nuclide Measurements

使用全大陆宇宙成因核素测量数据库对长期南极冰盖模型模拟进行天气评估

基本信息

批准号：
1744771
负责人：
Gregory Balco
金额：
$ 22.95万
依托单位：
Berkeley Geochronology Center
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-06-01 至 2022-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1744771&HistoricalAwards=false
关键词：
Synoptic Evaluation Long Term Antarctic

项目摘要

The purpose of this project is to use geological data that record past changes in the Antarctic ice sheets to test computer models for ice sheet change. The geologic data mainly consist of dated glacial deposits that are preserved above the level of the present ice sheet, and range in age from thousands to millions of years old. These provide information about the size, thickness, and rate of change of the ice sheets during past times when the ice sheets were larger than present. In addition, some of these data are from below the present ice surface and therefore also provide some information about past warm periods when ice sheets were most likely smaller than present. The primary purpose of the computer model is to predict future ice sheet changes, but because significant changes in the size of ice sheets are slow and likely occur over hundreds of years or longer, the only way to determine whether these models are accurate is to test their ability to reproduce past ice sheet changes. The primary purpose of this project is to carry out such a test. The research team will compile relevant geologic data, in some cases generate new data by dating additional deposits, and develop methods and software to compare data to model simulations. In addition, this project will (i) contribute to building and sustaining U.S. science capacity through postdoctoral training in geochronology, ice sheet modeling, and data science, and (ii) improve public access to geologic data and model simulations relevant to ice sheet change through online database and website development. Technical aspects of this project are primarily focused on the field of cosmogenic-nuclide exposure-dating, which is a method that relies on the production of rare stable and radio-nuclides by cosmic-ray interactions with rocks and minerals exposed at the Earth's surface. Because the advance and retreat of ice sheets results in alternating cosmic-ray exposure and shielding of underlying bedrock and surficial deposits, this technique is commonly used to date and reconstruct past ice sheet changes. First, this project will contribute to compiling and systematizing a large amount of cosmogenic-nuclide exposure age data collected in Antarctica during the past three decades. Second, it will generate additional geochemical data needed to improve the extent and usefulness of measurements of stable cosmogenic nuclides, cosmogenic neon-21 in particular, that are useful for constraining ice-sheet behavior on million-year timescales. Third, it will develop a computational framework for comparison of the geologic data set with existing numerical model simulations of Antarctic ice sheet change during the past several million years, with particular emphasis on model simulations of past warm periods, for example the middle Pliocene ca. 3-3.3 million years ago, during which the Antarctic ice sheets are hypothesized to have been substantially smaller than present. Fourth, guided by the results of this comparison, it will generate new model simulations aimed at improving agreement between model simulations and geologic data, as well as diagnosing which processes or parameterizations in the models are or are not well constrained by the data.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

该项目的目的是使用记录南极冰盖过去变化的地质数据来测试计算机模型是否变化。地质数据主要由日期的冰川沉积物组成，这些冰川沉积物保留在本冰盖水平以上，年龄从数千年到数百万年的年龄不等。这些提供了有关在过去的时间大于现在的时间，有关冰盖的大小，厚度和变化速率的信息。此外，其中一些数据来自目前的冰表面，因此还提供了一些有关过去温暖时期的信息，当时冰盖最有可能小于现在。计算机模型的主要目的是预测未来的冰盖变化，但是由于冰盖大小的显着变化很慢，并且可能发生了数百年或更长时间，因此确定这些模型是否准确的唯一方法是测试其复制过去冰盖变化的能力。该项目的主要目的是进行这样的测试。研究团队将通过与其他存款进行约会，并开发方法和软件将数据与模型模拟进行比较。此外，该项目将（i）通过在地质学，冰盖建模和数据科学领域的博士后培训以及（ii）通过在线数据库和网站开发与冰盖更改相关的地质数据和模型模拟来提高建筑和维持美国科学能力。该项目的技术方面主要集中在宇宙核核暴露日期的领域上，该方法依赖于通过宇宙射线与地球表面暴露于岩石和矿物质的宇宙射线相互作用而产生的稀有稳定核和无线电核的方法。由于冰盖的前进和撤退会导致宇宙射线的交替暴露以及遮盖底层基岩和表面沉积物的屏蔽，因此该技术通常用于日期和重建过去的冰盖变化。首先，该项目将有助于整理和系统化大量的宇宙基因核暴露年龄数据在过去的三十年中。其次，它将生成其他需要的地球化学数据，以提高稳定宇宙核素的测量程度和实用性，尤其是宇宙核苷-Neon-21，这对于在百万年的时间表上约束冰盖行为很有用。第三，它将开发一个计算框架，用于将地质数据集与过去几百万年的南极冰盖变化的现有数值模型模拟进行比较，并特别强调了过去温暖时期的模型模拟，例如中新世。 3-330万年前，在此期间，南极冰盖被认为比现在小得多。第四，在此比较结果的指导下，它将生成旨在改善模型模拟和地质数据之间一致性的新模型模拟，并诊断模型中的哪些过程或参数化对数据进行了或不太约束。该奖项反映了NSF的法定任务，并通过使用基金会的范围和广泛的评估来进行评估，并通过评估范围来进行评估。